Stats

  • Locked Locked
  • Replies 16
  • Subscribers 65
  • Views 21441
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Noise Figure of an upconverting mixer under input IF signal

bennys

I'm trying to simulate the noise figure of a transmit mixer as a function of input IF power. 

From the cadence tutorials it seems as if the HBnoise sim is performed under small signal conditions where the input IF port is set to DC

(for example in http://www.cadence.com/blogs/rf/archive/2011/03/10/tips-for-simulating-a-transmit-mixer-in-spectrerf.aspx, its stated "If you are running PAC or Pnoise, you set the IF sourcetype to dc so that the LO is the only sinusoid in the system (Edit Properties on your IF port in the schematic). Since the input for this example is sinusoidal, we will choose Harmonic Balance. " )

How whould you recommend to perform a noise figure sim with IF signal applied.

 

In addition when I look at the noise separation print form it shows that the noise of the mixer comes from a biasing circuit which is AC disconnected from the circuit..., this must be an artifact and can not be the real noise source of the mixer, not sure but maybe you have some input on this as well? 

Parents

  • Hi Bennys,

    just a couple of random thoughts. I guess that in a TX mixer the IF input is 'small signal' anyways, meaning that its amplitude should be well within the range of linear behavior of the IF port, as to avoid introducing distortion. Under this view, one can make full use of the NF concept, which is indeed a 'small signal' concept.

    You may still want to see whether the NF changes while the IF signal changes, but for this you could just analyze your circuit under different DC inputs. In the range foreseen for the IF signal, however, you should not see any appreciable difference...Well, I guess :)

    As for the noise contributions, I think it is entirely possible that the low frequency noise introduced by the bias circuitry gets upconverted and you find it in the contributors @TX frequency.

    I never tried them myself but for sure Spectre RF allows you to simulate multitone stimuli, either commensurate (HB) or not (QPSS), or also ENV, if you want to explore things further.

    My two cents,

    Michele 

Reply

  • Hi Bennys,

    just a couple of random thoughts. I guess that in a TX mixer the IF input is 'small signal' anyways, meaning that its amplitude should be well within the range of linear behavior of the IF port, as to avoid introducing distortion. Under this view, one can make full use of the NF concept, which is indeed a 'small signal' concept.

    You may still want to see whether the NF changes while the IF signal changes, but for this you could just analyze your circuit under different DC inputs. In the range foreseen for the IF signal, however, you should not see any appreciable difference...Well, I guess :)

    As for the noise contributions, I think it is entirely possible that the low frequency noise introduced by the bias circuitry gets upconverted and you find it in the contributors @TX frequency.

    I never tried them myself but for sure Spectre RF allows you to simulate multitone stimuli, either commensurate (HB) or not (QPSS), or also ENV, if you want to explore things further.

    My two cents,

    Michele 

Children
No Data

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.